Impeller for centrifugal pump



United States Patent 3,347,167 III/WELLER FUR CENTRIFUGAL PUMP Elmer .l. Nelesen, West Allis, Wis., assignor to General Electric Company, a corporation of New York Filed Feb. 24, 1966, Ser. No. 529,766 4 Claims. (til. 1ti33) This invention relates to pumping apparatus, and more particularly to centrifugal pumping apparatus wherein a fluid impeller is adapted to be selectively driven in opposite directions of rotation, the impeller being effective to discharge fluid from the pump while rotating in one direction, and being substantially ineffective to discharge fluid while rotating in the opposite direction.

Although not limited thereto, my invention is particularly adaptable to automatic dishwashers which normally include a recirculating pump and a centrifugal drain pump with the impeller means of each pump being mounted on the rotor shaft of a reversible electric motor. When the shaft rotates in a first direction, the recirculating pump impeller is effective to distribute water throughout the wash chamber, while the impeller means of the drain pump is in an essentially inoperative condition to avoid removing fluid from the wash chamber. When the direction of rotation of the rotor shaft is reversed, the impeller means of the drain pump shifts to an operative condition, wherein it is then effective to remove fluid from the wash chamber of the dishwasher.

conventionally, the impeller means of the drain pump has included a number of pump blades which were secured to a pump plate located in a secondary chamber below the wash chamber. The pump blades were pivotally secured to the pump plate adjacent a central hub which mounted the pump plate on the rotor shaft. During rotation of the pump plate in the direction in which no pumping or drain action was desired, I found that the centrifugal forces engendered during rotation tended to force the blades outwardly from the central hub and toward their pump-out or discharge position, the water pressure on the blades'being inadequate to maintain them in a position substantially tangential to the central hub where they would offer the least resistance to the flow of water. The outward movement of the blades when they were supposed to be tangential to the central hub had the effect of removing some of the fluid necessary for the wash and rinse operations of the dishwasher. In addition, the movement of the blades toward their pump-out position increased the power requirement on the motor, in that both the recirculating pump and the drain pump were operating against an external force; the additional drag of the drain pump thereby producing an undesirable wattage draw on the motor.

It is, accordingly, a primary object of my invention to provide an improved pumping apparatus which overcomes the aforementioned problems. It is a further object of my invention to provide, in a pump having a pump plate adapted to rotate in opposite directions, at least one pump blade which is pivotally secured to the pump plate and wherein means is provided on the pump plate for effectively and automatically positioning the blade in its operative and inoperative positions when the plate is selectively rotated in the opposite directions.

It is yet a further object of my invention to provide on a pump plate adapted to rotate in opposite directions, at least one pump blade which is pivotally secured to the pump plate and which shifts between operative and inoperative positions depending on the direction of rotation of the pump plate, and wherein the centrifugal forces engendered during rotation of the plate in one direction aid in maintaining the pump blade in its inoperative position, whereby the power requirements of the pump are reduced during this direction of rotation.

3,347,167 Patented Oct. 17, 1967 In one aspect of my invention, I provide in a centrifugal type pump having a chamber with an axial inlet opening thereto and a peripheral discharge passage therefrom and a pump plate disposed Within the chamber and secured at its center to a reversible drive means, whereby the plate may be selectively rotated in opposite directions relative to said chamber, the improvement including at least one pump blade pivotally secured to the plate near the outer periphery thereof; the blade being movable between an operative position when the plate is rotated in one direction and wherein the blade is substantially radially directed and is effective to translate fluid from the inlet opening, through the chamber, and out the discharge passage, and an inoperative position when the plate is rotated in the opposite direction and the blade is substantially tangentially directed and is ineffective to translate fluid through the chamber. First and second stop means are provided on the plate in the path of movement of the blade, the first stop means being effective to fix the motion of the blade in its operative position when the plate is rotating in one direction, and the second stop means maintaining the blade in its inoperative position, whereby the blade is substantially ineffective to remove fluid from the chamber when the plate is rotating in the opposite direction.

Other features and advantages of my invention will be apparent from the following detailed description of a presently preferred embodiment thereof, read in connection with the accompanying drawing in which:

FIGURE 1 is a side elevational view in partial cross section of a dishwasher including a pump embodying my improved pump plate;

FIGURE 2 is an enlarged fragmentary view illustrating the motor and pump assembly of the dishwasher of FIGURE 1 in greater detail;

FIGURE 3 is a plan view of the pump plate and blade assembly which illustrates the position of the pump blades in their operative position when the pump plate is rotating in the pump-out direction during the drain cycle of the dishwasher; and

FIGURE 4 is a partial plan view similar to FIGURE 3, and shows the position of the blades in their inoperative position when the pump is rotating in the wash and rinse direction.

Referring first to FIGURE 1, my invention is shown in an otherwise conventional domestic dishwasher in which an outer casing 1 includes suitable structure 2 for the support of the dishwasher tub, or chamber, 3. The tub and outer structure are constructed to provide registering front wall openings, with respect to which a door 4 is hinged at its bottom (hinges not shown) so as to swing between the normally closed vertical position as shown in FIG- URE 1, and a horizontal open position. Suitable gasket means (not shown) are normally interposed between the door and the periphery of the tub opening to provide for sealing against the leakage of water during operation of the machine.

A pair of vertically spaced racks 5 and 6 are provided within tub 3. Each of the two racks is formed of Wire in the conventional manner so as to receive, in suitable position for washing, a varied assortment of dishes, glassware, and the like (not shown). Also, each of the two racks is mounted so as to move horizontally forward (to the left as viewed in FIGURE 1) when door 4- is opened, so that the articles in the racks are accessible for loading and unloading purposes. The racks 5 and 6 may be supported in any conventional way, one such support system being shown by Fitzpatrick and Krzewina, in US. Patent No. 3,288,302, for Support System and assigned to the General Electric Company, assignee of the present invention.

A conventional time cycle control 7 is mounted on a 9 convenient location in the upper portion of door 4. By well known circuitry, control 7 is arranged to control the operating mechanism disposed in a machinery compartment 8 below the tub, programing the mechanism so as to provide a desired sequence of washing and rinsing operations, and a final drying operation. The mechanism within compartment 8 may include for instance a solenoid valve 9 connected by piping 10 to a hot water supply (not shown) and supplying water to tub 3 by way of a pipe 11 arranged in relation to a side wall inlet fitting 12 so as to provide the oneinch air gap generally required by plumbing codes.

The operating components further include a pump 13 arranged to be driven by a reversible electric motor 14 and providing for recirculation of water from the sump portion 15 of the tub through a cylindrical pump dis charge outlet 16. The details of the pump arrangement are illustrated in FIGURE 2, and will be discussed in detail herebelow, after the general description of the dishwasher is completed.

The operating mechanism may further include a conventional pressure operated switch, schematically shown at 17, which, by well known electrical circuitry, will open the solenoid valve 9 to prevent accumulation of more than a pre-determined amount of water within the dishwasher tub.

Outlet 16 of pump 13 communicates with a reaction type spray arm 18 having orifices arranged in the usual way, so that upon issuance of water therefrom spray arm 13 is caused to rotate, the water upon issuance providing a cleansing effect on the dishes contained in racks and 6. In addition to the spray arm 18, the dishwasher may include a conduit 19 leading from the spray arm up to another water discharge device, such as that shown at, 20, which is particularly suited to discharge liquid between the racks 5 and 6. This has the effect of improving the washing of articles in rack 5 and of rinsing down any food particles which may be on the articles in rack 6. It will be understood that member 20 may either be rotated by mechanical connection to spray arm 18 through conduit 19, or by having jet orifices of its own to provide the reaction force necessary for rotation.

Referring now to FIGURE 2, the details of the pump and motor assembly including my improved pump plate will now be described in greater detail. As stated heretofore, the function of recirculating pump 13 is to force water up through spray arm 18 and member 20. This recirculation system normally includes an annular inlet 15A to pump 13, the inlet being provided with any suitable screening or filter device such as that shown at 21.

The recirculating pump assembly .13 is usually of the centrifugal type, and includes an upper shroud or cover 22 which may be secured to the pump base 23 by any suitable means, such as spring clips (not shown). Pump base 23 is secured to the sump portion 15 of the tub by three hold down bolts 24 which extend through the filter 21 and the bottom of the tub, and are then threaded into speed nuts 25 which are clippedto the under side of the tub. Mounted within the shroud or cover 22 and pump base 23 is the impeller assembly 26, which includes impeller ribs 27 that force the recirculating water outward and upward within the pump, where it is then diverted by the shroud or cover 22 from the normal radial pattern to the vertical flow through outlet 16. The impeller assembly 26 is secured to the rotor shaft 28 of the motor by means of a bolt 29 which passes through the impeller assembly and is then threaded into the rotor shaft at the top end thereof.

Secured to the bottom of the dishwasher tub is a mounting plate 30, which has an opening 31 therethrough substantially coextensive with the drain opening 32 in the sumpportion 15 of the dishwasher. Mounting plate 30 also includes a downwardly extending annular flange 33 which has an outwardly extending circular ridge 34 formed thereon. The motor housing and bearing assembly 35 is secured to flange 33 by way of a neoprene rubber collar 36, the bottom portion of which is slipped over the top of the motor housing, while the upper section overlies flange 33 of the mounting plate. Upper and lower mounting bands 37 and 38 are secured about collar 36, with the lower band 38 overlying an outwardly extending annular head 39 formed at the top of housing assembly 35, and the upper band 37 overlying the circular ridge 34 of flange 33. When bands 37 and 38 are tightened, the motor assembly 35 will be securely fastened to the bottom of the dishwasher.

The area between the bottom mounting plate 30-and the top of the motor housing 35 defines a second pump chamber 4% within which is mounted the pump plate 41, described in detail herebelow. Included within the second pump chamber above pump plate 41 is a drain or bafile plate 42, which has an opening 43 therethrough substantially coextensive with the drain openings 31 and 32 of the tub and mounting plate respectively. Drain plate 42 is interposed between the top of housing assembly 35 and the bottom of flange 33 of mounting plate 30. Suitable adaptor gaskets 44 are disposed on rotor shaft 28 between the bottom of the impeller assembly 26 and the top surface of pump plate 41, and immediately below the pump plate 41 is a mating ring 45 which functions as a rotating seal for the pump plate. A water seal 46 is disposed below the mating ring, the function of which is to prevent passage of water from the second pump chamber onto the motor assembly 14 disposed therebelow. A spacer bushing 47 is located in the center of the water seal assembly and maintains the proper space between water seal 46 and mating ring 45. This is accomplished by the rotor shaft 28 and mating ring bearing on the spacer bushing when impeller bolt 29 is tightened.

The motor housing 35 also includes an outlet structure 48 from the second pump chamber; 40 located just below pump plate 41. Outlet 48 communicates with a conduit 49 which carries vitiated fluids from the dishwasher to any suitable sewer or septic line (not shown) when the pump plate is rotating in thedirection shown in FIG- URE 3. The conduit 49 may be secured to outlet, 48 by any suitable means, such as a corbin clamp 50.

The preferred embodiment of the pump plate 41 is illustrated in FIGURES 2 and 3, and is seen to include a raised central hub portion 51 having .a suitable opening 52 therethrough which matches the configuration of rotor shaft 38. The hub portion 51 is bounded by a fiat peripheral plate portion 53 which carries a plurality of circumfercntially spaced pump blades 54 thereon. Each blade includes abody portion 55 extending upwardly from the flat plate 53 and disposed in a plane perpendicular thereto. Each blade is rotatably secured at one end to plate 53 near the outer periphery thereof by any suitable means, such as rivets 56; each rivet providing a vertical pivot axis for the body portion 55,,the pivot axis thereby being perpendicular to the plane of the flat plate portion.

The position of blades 54 during the wash and rinse cycles of the dishwasher is illustrated in FIGURE 4. During these cycles, rotor shaft 28 rotates in a counterclockwise direction as indicatcd by the arrow on hub portion 51 in FIGURE 4. The flow of Water relative to the direction of rotation of the plate is in the clock-wise direction as illustrated by the arrow positioned on the flat plate porw tion 53. The water pressure on the blades will cause them to pivot about vertical axis 56 to a position substantially tangential to the outer periphery of plate 53 as shown in FIGURE 4. In this position, the centrifugal forces engendered by rotation of the plate will now act to keep the blades parallel to the flow of water, instead of forcing the blades to their pump-out position as has been the problem heretofore. The blades are essentially inoperative in this position, in that they offer the least amount of resistance to the flow of water so that there will be a minimal amount of water discharged through conduit49.

It will be observed from FIGURE 4 that the free end of blade 54 is positioned radially closer to the center of the shaft than is the end secured to the pivot axis 56. This is necessary to insure that there will be a sufficient moment arm directed radially inward from the pivot axis, which, when the direction of rotation of the plate is reversed, will give the blade sufficient inertial force to pivot toward the operative position shown in FIGURE 3. Also, by positioning the blade in this manner, the water in the second pump chamber provides additional force to the blade to help pivot it to its operative position. I have found that the most desirable location for the blade which will provide both the minimal resistance to water flow and yet insure rotation from the inoperative to operative positions, is when the blades are disposed at an angle of 65 to 70 from their radial or operative position.

At the cessation of each wash and rinse cycle, it is desirable to remove the vitiated fluid from the wash chamber and replace it with fresh water. At this time, the direction of rotation of plate 41 and the position of the blades 54 is illustrated in FIGURE 3. The plate will now rotate in the clock-wise direction as illustrated by the arrow on hub portion 51. The relative flow of water within the secondary pump chamber 40 will be in the direction shown by the arrows on the flat plate portion 53, and the blades 54 will shift to their operative or pump-out position under the combined inertial and water forces on the blade. In their operative position, the blades are directed radially inward as illustrated in FIGURE 3, so as to be substantially perpendicular to the flow of water. This will effectively force the water out of discharge opening 48 and through conduit 49.

To maintain the pump blades in their operative and inoperative positions, that is, directed radially inward and perpendicular to the flow of water during the pump-out cycle, and substantially parallel to the flow of Water and the periphery of the flat plate portion during the wash and rinse cycles, I have provided the first and second stop means, 57 and 58 respectively, for the pump blades which position the blades at the most efficient location for the desired direction of rotation. I have found that the most economical way to provide the stop means is to form them as an integral portion of the plate, either by embossing the plate or, as illustrated, providing stop tabs which are struck from the plate 41 at the time the opening 52 and raised hub portion 51 are formed thereon.

The first stop tab 57 is provided adjacent the raised hub portion, the tab being directed radially inward and offset [from the pivot axis 56 of the blade by the thickness of the body portion 55 of the blade, to insure that the blade will be substantially perpendicular to the flow of water for maximum pump-out efficiency. The second stop tab 58 for each blade is positioned near the periphery of the flat plate portion and is substantially parallel thereto, to insure that the blade will be positioned substantially parallel to the flow of water and will therefore be ineffective to pump out any water during this direction of rotation.

From the foregoing, it is apparent that I have provided an improved reversible pump plate for a dishwasher or the like. In my present arrangement, the blade is positively positioned in its respective locations to insure maximum efiiciency in each direction of rotation. By locating the pivot axis near the outer periphery of the plate por tion, I have taken advantage of the forces acting on the blade to maintain it parallel to the flow of water and prevent any pump-out of water when the plate is rotating in the desired direction, contrary to the result which occurs when the pivot axis of the blade is located substantially adjacent the hub portion as has heretofore been mentioned. The location of the pivot point and the use of the tab stops to maintain the blades substantially parallel to the flow of water thus reduces the wattage required to rotate the plate, as there is less resistance to overcome.

While there has been described what is at present thought to be the preferred embodiment of my invention,

it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

I claim:

1. In a centrifugal type pump having a chamber with an axial inlet opening thereto and a peripheral discharge passage therefrom and including a pump plate disposed within said chamber and operatively secured at the cen ter thereof to reversible drive means for selectively rotating said plate in opposite directions relative to said chamber, the improvement comprising:

(a) at least one pump blade pivotally secured to said plate near the outer periphery thereof;

(b) said blade being movable between an operative position when said plate i rotated in one direction and wherein said blade is substantially radially directed and is effective to translate fluid from said inlet opening, through said chamber, and out said discharge passage, and an inoperative position when said plate is rotated in the opposite direction and said blade is substantially tangentially directed and is ineffective to translate fluid through said chamber; and

(c) first and second stop means disposed on said plate in the path of movement of said blade, said first stop means being effective to fix the motion of said blade in its operative position when said plate is rotating in said one direction, and said second stop means being effective to fix the motion of said blade in its inoperative position whereby said blade is substantially ineffective to remove fluid from said chamber when said plate is rotating in said opposite direction.

2. The combination according to claim 1 wherein said blade is pivotally mounted about an axis perpendicular to the plane of said plate, said blade in its operative position extending radially from the pivot axis thereof toward the center of said plate and being substantially perpendicular to the flow of fluid relative to said plate when said plate is rotating in said one direction; and said blade in its inoperative position having a relatively small radial component of direction whereby said blade extends substantially parallel to the flow of fluid relative to said plate and offers substantially little resistance to the flow of fluid over said plate when said plate is rotating in said opposite direction; said slight radial component of direction of said blade creating sufiicient inertial force on said blade to cause said blade to pivot to its operative position when the direction of rotation of said plate is reversed from said opposite direction to said one direction.

3. The combination according to claim 2 wherein said pump plate includes a flat plate portion and a cylindrical hub portion for supporting said fiat plate portion on said reversible drive means; and said blade extends from said pivot axis near the outer periphery of said plate and terminates substantially adjacent said hub when said blade is in its operative position.

4. The combination according to claim 2 wherein said first and second stop means are formed as upwardly extending integral portions of said plate.

References Cited UNITED STATES PATENTS 2,838,002 6/1958 Cohen 103-3 3,033,015 5/1962 Stutrud 68-23 FOREIGN PATENTS 172,741 6/ 1906 Germany.

185,139 8/1922 Great Britain. 324,714 2/1930 Great Britain. 528,439 5/1940 Great Britain.

DONLEY J. STOCKING, Primary Examiner.

H. F. RADUAZO, Assistant Examiner. 

1. IN A CENTRIFUGAL TYPE PUMP HAVING A CHAMBER WITH AN AXIAL INLET OPENING THERETO AND A PERIPHERAL DISCHARGE PASSAGE THEREFROM AND INCLUDING A PUMP PLATE DISPOSED WITHIN SAID CHAMBER AND OPERATIVELY SECURED AT THE CENTER THEREOF TO REVERSIBLE DRIVE MEANS FOR SELECTIVELY ROTATING SAID PLATE IN OPPOSITE DIRECTIONS RELATIVE TO SAID CHAMBER, THE IMPROVEMENT COMPRISING: (A) AT LEAST ONE PUMP BLADE PIVOTALLY SECURED TO SAID PLATE NEAR THE OUTER PERIPHERY THEREOF; (B) SAID BLADE BEING MOVABLE BETWEEN AN OPERATIVE POSITION WHEN SAID PLATE IS ROTATED IN ONE DIRECTION AND WHEREIN SAID BLADE IS SUBSTANTIALLY RADIALLY DIRECTED AND IS EFFECTIVE TO TRANSLATE FLUID FROM SAID INLET OPENING, THROUGH SAID CHAMBER, AND OUT SAID DISCHARGE PASSAGE, AND AN INOPERATIVE POSITION WHEN SAID PLATE IS ROTATED IN THE OPPOSITE DIRECTION AND SAID BLADE IS SUBSTANTIALLY TANGENTIALLY DIRECTED AND IS INEFFECTIVE TO TRANSLATE FLUID THROUGH SAID CHAMBER; AND (C) FIRST AND SECOND STOP MEANS DISPOSED ON SAID PLATE IN THE PATH OF MOVEMENT OF SAID BLADE, SAID FIRST STOP MEANS BEING EFFECTIVE TO FIX THE MOTION OF SAID BLADE IN ITS OPERATIVE POSITION WHEN SAID PLATE IS ROTATING IN SAID ONE DIRECTION, AND SAID SECOND STOP MEANS BEING EFFECTIVE TO FIX THE MOTION OF SAID BLADE IN ITS INOPERATIVE POSITION WHEREBY SAID BLADE IS SUBSTANTIALLY INEFFECTIVE TO REMOVE FLUID SAID CHAMBER WHEN SAID PLATE IS ROTATING IN SAID OPPOSITE DIRECTION. 